How can I get rendered animation to video instead of a bunch of pictures
Use the Video Sequence Editor to load your rendered image sequence and compile into a video format. This is the conventional means of creating a video with 3d modeling/animation software because compositing is often required for the final product. It takes very little time to compile a video from an image sequence within Blender and you will still have your higher quality image stills if you need to do editing later.

If you still insist on making video directly from your render (not recommended, as you may find you aren't happy with the settings, or artifacts may appear in the video that you can't weed out), you can do that by changing your render file format (Output panel -> Output section -> File Format drop-down) to one of the 3 options under "Movie". Obviously, this will force you to render everything from scratch.

Video Sequencer Example:

I rendered a couple of image sequences from the NLA Editor overnight and am outputting to video right now. Here is how I did that.

Go to the animation tab and/or select the Video Sequencer panel. Then from the menu (those horizontal white bars), you want to choose Add -> Image/Image Sequence:



A file selection view will open. To make sure you have what you need (you will be surprised how it doesn't work sometimes), Choose the start and end frame in the options to the left, and the channel (that is, the layer) you want those images to be placed in, AND box-select (tap B-key, click-and-drag) the image files you want to be used in sequence.  If you only want a single file, follow these same instructions but make the start and end frame the same.



Once you do that, a strip will appear in the channel you chose in the Video Sequence editor. You can select it, press the G key and move it forward or back in time, or even into other channel positions. If you press the N key, you will see options that allow you to extend or crop the image sequence.



I am duplicating the first strip twice using ctrl-C, ctrl-v, and moving them into position. You do not have to have each strip on a separate channel. The third instance of this strip is needs a copy of the first frame so I added that the same way I imported the first strip, but with start and end frames being frame 0.  The latter sequences were saved to a different directory but I still add that one the same as the first. I copied the last frame for one of those and stretched it out over 8 frames using the context menu (N key).



As you scrub the play head (or press "play" on the Timeline), the video sequencer will tick through the animation and play it at full speed once it is loaded (it may still be crunchy if you are low on memory). Here is a gif of that happening:



I copied all those film strips in all those channels 3 times to make an animation that is about 14 seconds (my framerate is set in the Output panel to be 30 fps). Then I was ready to export to video format.

Exporting to video is done in the rendering panel on the right. I selected the mpeg option under file output with high quality settings, Matroska container, and H.264 video codec (those settings are in the video drop down that opens in the rendering panel once you select a video file format).



I do not show this but you want to check Sequencer under the Post Processing drop-down and make sure you have "Frame Start" and "End" set to the beginning and end frames of your animation sequence. Step size should be 1.

Finally, choose Render -> Animation from the top drop-down menu, and wait. This will compile significantly faster than your images took to render.



You can see the result here:

https://youtu.be/LY7LGA8AMr0